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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Wed, 1 May 2024 04:44:16 -0400
Message-ID: <CANzqJaBUzsKzGhGyhUNk1kXNqixOOL9RoKi3G323aVacFu0WpA@mail.gmail.com>
Subject: Re: Posgresql 14 and CarbonBlack on RHEL8?
To: pgsql-general <pgsql-general@postgresql.org>
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Archived-At: <https://www.postgresql.org/message-id/CANzqJaBUzsKzGhGyhUNk1kXNqixOOL9RoKi3G323aVacFu0WpA%40mail.gmail.com>
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On Tue, Apr 30, 2024 at 10:07=E2=80=AFPM Tom Lane <tgl@sss.pgh.pa.us> wrote=
:

> Ron Johnson <ronljohnsonjr@gmail.com> writes:
> > When running stress tests on the systems (in prod, during the maintenan=
ce
> > window), 171K events/second are generated on the RHEL8 servers, and CB
> > needs (according to top(1)) 325% of CPU to handle that, and still
> dropping
> > 92% of them.
> > The RHEL6 system doesn't bat an eye at running the exact same test (36
> cron
> > jobs running psql executing SELECT statements).
>
> Is JIT enabled on the newer system?  If so try turning it off, or else
> raise the associated cost settings.  We've seen lots of reports of
> workloads where, by default, the planner is too aggressive about
> applying JIT.
>

A puzzling suggestion.  Why should it impact AV software?

At one point, I disabled JIT to test its impact on PG, performance was a
bit of a wash (some queries were a bit faster, some were a bit slower), but
I didn't monitor CB.

Just now, I did ALTER SYSTEM SET jit=3D'off'; and re-ran the stress test.  =
No
impact to CarbonBlack.

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<div dir=3D"ltr"><div dir=3D"ltr">On Tue, Apr 30, 2024 at 10:07=E2=80=AFPM =
Tom Lane &lt;<a href=3D"mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt;=
 wrote:<br></div><div class=3D"gmail_quote"><blockquote class=3D"gmail_quot=
e" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204)=
;padding-left:1ex">Ron Johnson &lt;<a href=3D"mailto:ronljohnsonjr@gmail.co=
m" target=3D"_blank">ronljohnsonjr@gmail.com</a>&gt; writes:<br>
&gt; When running stress tests on the systems (in prod, during the maintena=
nce<br>
&gt; window), 171K events/second are generated on the RHEL8 servers, and CB=
<br>
&gt; needs (according to top(1)) 325% of CPU to handle that, and still drop=
ping<br>
&gt; 92% of them.<br>
&gt; The RHEL6 system doesn&#39;t bat an eye at running the exact same test=
 (36 cron<br>
&gt; jobs running psql executing SELECT statements).<br>
<br>
Is JIT enabled on the newer system?=C2=A0 If so try turning it off, or else=
<br>
raise the associated cost settings.=C2=A0 We&#39;ve seen lots of reports of=
<br>
workloads where, by default, the planner is too aggressive about<br>
applying JIT.<br></blockquote><div><br></div><div>A puzzling=C2=A0suggestio=
n.=C2=A0 Why should it impact AV software?</div><div><br></div><div>At one =
point, I disabled JIT to test its impact on PG, performance was a bit of a =
wash (some queries were a bit faster, some were a bit slower), but I didn&#=
39;t monitor CB.</div><div><br></div><div>Just now, I did ALTER SYSTEM SET =
jit=3D&#39;off&#39;; and re-ran the stress test.=C2=A0 No impact to CarbonB=
lack.</div><div><br></div></div></div>

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